Day-night flash beacon

ABSTRACT

A flash beacon in which the same bulb is operated in two different modes by a single power supply. A first discharge capacitance operates the lamp in a single flash mode and a second smaller discharge capacitance operates the lamp in a multiple discharge mode with the smaller discharge capacitance being recharged by the first discharge capacitance. A light sensitive relay operates to switch the beacon from a single flash mode in day time to a multiple flash mode at night.

United States Patent 1 91 Kearsley Nov. 5, 1974 [5 DAY-NIGHT FLASH BEACON 3,165,669 1/1922 Marjcotte 3155541 5 ux 3,234,431 2/19 B c 3l5 41 P UX [75] Inventor: Wayne Kearsley Chelmsford, 3,286,128 11/1966 ii TC? 320/1 x Mass 3,430,159 2/1969 1166161 315/241 R x 3,515,938 6/1970 Morse 315/24] R X [73] Asslgnee' i ii s l z g g ig g 3,666,964 5/1972 Flynn 320/1 x 7 1 [22] Filed: July 27, 1972 Primary Examinerl)onald J. Yuskd [21] Appl. No.1 275,720

[57] ABSTRACT 52 US. Cl 340/105 315/159 315/241 A flash beacon in which the Same bulb is Operated in 51 1111.0. 11056 41/32 two different-modes by a Single POWer PP Y- A first [58] Field of Search 340/25 28 5O 77 81 R discharge capacitance operates the lamp in a single 340/105 343 3 flash mode and a second smaller discharge capaci- 156 1 59 CD 227R 241 tance operates the lamp in a multiple discharge mode i P 241 11 with the smaller discharge capacitance being recharged by the first discharge capacitance. A light [56] References Cited sensitive relay operates to switch the beacon from a UNITED STATES PATENTS single flash mode in day time to a multiple flash mode at ni ht. 2,895,080 7/1959 Branker 315/240 x g 3,027,491 3/1962 5 Clalms, 2 Drawing Flgures Seidler 315/159 POWER SUPPLY a? l l LIGHT MULTIPLE T SENSITIVE TRIGGER SS E RELAY GENERATOR PATENIEDnuv 5 m4 CAPACITOR 1916c HmmE SUPPLY DAY-NIGHT TRIGGER BEACON CIRCUIT L LIGHT SENSITIVE RELAY N74 POWER SUPPLY a? T E- LIGHT MULTIPLE T SENSITIVE TRIGGER L ';5

RELAY GENERATOR DAY-NIGHT FLASH BEACON BACKGROUND OF THE INVENTION:

l. Field of the Invention:

The present invention relates to flash type beacon It is a further object of the invention to provide a single aircraft warning beacon suitable for use in both daylight and night conditions.

lights and particularly those used as tall structure warning signals for aircraft.

2. Description of the Prior Art:

the greater height of present structures, it has become necessary to use warning lights for all conditions of visibility day, night and fog. For effective use in the daytime high intensity xenon flash beacons are coming into extensive use. V

The intensity of these beacons is useful also to pierce fog fora considerable range. However, the high intensity beacons are too intense for satisfactory use at night, Not only are they a cause ofcomplaint for people on the ground, in nearby buildings. and in cars, but they are also uncomfortable for aircraft pilots. The flashes are so intense as to saturatevision and are so short in duration that their location is hard to pinpoint. Accordingly, flash beacons for daytime use have been unsuitable for night use and separate night systems are conventional.

My U.S. Pat. No. 3,737,645 describes a flash beacon with unusually low output below the beam axis so as to reduce annoyance to people on the ground. However, the single high intensity flashes still reflect from other tall structures in the vicinity and have the deficiencies already mentioned with respect to aircraft pilots.

It is readily possible to switch the discharge supply of a flash system to smaller voltage to lower the output. However. if the voltage is lowered, the flashtube efficiency is lower and it is more likely to misfire. If the ca pacity is switched to a smaller value with the same voltage. the flash duration is short and particularly difficult to pinpoint. For a given intensity, shorter flashes have also been shown to be more annoying.

Modulated or flickering flashes have been used in the past as described for example in U.S. Pat. No. 3046.448. However, devices such as these have not been used for multiple mode operation.

SUMMARY OF THE INVENTION:

In accordance with the present invention, a day-night mode beacom system is provided using a capacitive discharge system to operate high intensity flashtubes. In daytime use, a large capacitor or battery of capacitors provides high power single flash discharges to the flashtube. At night, a light sensitive relay switches the flashtube across a smaller capacitor or battery of capacitors which is charged from the first capacitor. The charging rate of the second capacitor being controlled to provide discharges at a rate of between 20 and 120 per second in groups. The light sensitive relay also switches a trigger generating circuit to provide single or group triggers in accordance with the flash mode.

Thus, it is an object ofthe invention to provide a flash beacon that provides single high intensity flashes in daylight and multiple flashes of lower power at nighttime.

It is a further object of the invention to provide a capacitive discharge system selectively delivering relatively high power single discharges and relatively low power multiple discharges.

Further objects and features of the invention will be better understood upon reading the following description together with the drawing.

BRIEF DESCRIPTION OF THE DRAWING:

FIG. 1 is a block diagram of a day-night beacon system according to the invention.

FIG. 2 is a schematic diagram partially in block of the. beacon system of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

Flash beacons today conventionally include a flash discharge lamp such as a xenon flashlamp, a capacitive discharge power supply and a trigger circuit to provide a high voltage ionization pulse for triggering the discharge through the flashtube.

In a preferred embodiment of the present invention a day-night beacon 10 is suitably a xenon flashlamp in a reflector such as described in my U.S. Pat. No. 3,737,645.

Dual-mode trigger circuit 11 provides high voltage ionization pulses to the flashlamp in beacon 10 and dual-mode capacitive discharge supply 12 provides high current discharges to the flashlamp each time it is ionized by trigger circuit 11.

For use in daylight trigger circuit 11 preferably provides trigger pulses at a rate of between 30 and 60 pulses a minute. For use. of the inventive beacon for marine purposes slower trigger rates could be used. However, at the high speeds of modern aircraft it is necessary to give the warning flashes in fairly close repetition.

Light sensitive switch 14 is connected to switch both trigger circuit 11 and capacitive discharge 12. As dark approaches, light sensitive switch 14 switches operating further relays or gates in circuit 11 and supply 12. The

relays or gates in trigger circuit 11 switch the triggercircuit to supply groups of trigger pulse-s in which each group contains pulses at the rate of l 5 to l20'pulses per second and the groups are provided at the same rate as the single daylight flashes. The duration of each group is preferably in the range of 0.1 to 0.5 seconds. Shorter groups make it difficult for airplane pilots to pinpoint the flash source and longer groups are unnecessary and thus inefficient. The relay in supply 12 switches the discharge capacitor to a smaller capacity.

In FIG. 2 a simplified schematic of capacitive discharge supply 12 is given along with day-night beacon l0, depicted diagrammatically, and trigger circuit 11 depicted in more detailed block form.

Capacitive discharge supply 12 is conventional for purposes of the single flashes. Thus, it comprises a high voltage transformer 15 followed by a fullwave bridge rectifier l6 charging a capacitor 17. Capacitor 17 is connected across flashtube 18 of beacon 10 through coil 20. Coil 20 determines the shape and duration of the discharge pulse through tube 18.

For night use, second smaller capacitor 21 is connected across flash'tube 18 by relay contact 22 with is in series between capacitor 17 and coil 20. Capacitor 17 has preferably at least five times the capacity of capacitor 21. Thus. when relay contact 22 switches, capacitor 17 is disconnected from coil 20 and capacitor 21 is connected. Bypassing relay contact 22 and connecting capacitor 17 to coil 20 is a series combination of resistor 24, choke 25 and rectifier 26. This series connection provides a charging path to capacitor 21 when contact 22 is in the nighttime position.

Choke 25 has the main purpose of preventing sufficient current from capacitor 17 passing through the charging path of capacitor 21 to maintain flashtube l8 ionized. lt has a secondary effect of permitting the voltage on capacitor 21 to exceed the voltage on capacitor 17. However, since this voltage could reach close to double that of capacitor 17, resistor 24 operates to limit the voltage on capacitor 21.

Rectifier 26 blocks reverse current thus preventing any undesirable oscillation. Day-night beacon 10 is depicted as having a reflector 27 and as having a trigger 20 wire 28 encircling lamp 18 for ionizing trigger pulses. Trigger circuit 11 is depicted as having a pulse transformer 30 with its secondary connected to trigger wire 28 and its primary connected to capacitor 31, SCR (silicon control rectifier) 32 and a power supply 34.

This part of the trigger circuit is conventional with power supply 34 charging capacitor 31 which is then discharged through the primary of transformer 30 by triggering SCR 32 into conduction. The triggers for SCR 32 are provided by trigger generator 35 and multiple trigger generator 36.

Relay contact 37 connected from the gate of SCR 32 is operated by the switch in light sensitive switch 14. In daytime operation relay contact 37 connects the gate of SCR 32 to trigger generator 35. Trigger generator 35 o is suitably a multivibra tor having the frequency of the daytime flashing rate.

For nighttime operation relay 37 switches to connect generator 36 to the gate of SCR 32. Multiple trigger generator 36 as depicted is actuated by triggers from trigger generator 35.

While many conventional circuits are suitable, generator 36 may conveniently be a monostable multivibrator which switches for a predetermined interval of time upon each trigger from generator 35 and then switches back. During the on-time ofthe monostable multivibrator, its output would provide an enable voltage to a free running multivibrator providing triggers to SCR 32.

Trigger circuit ll can also be made using many alternative gating. counting or oscillating circuits other than those described for generators 35 and 36. It will also be recognized that generators 35 and 36 can be simple digital circuits and that relay contact 37 can be digital gates controlled by relay 14.

While the invention has been described with relation to a specific embodiment, various alternative arrangements will be obvious to those skilled in the art without departing from the contemplation of the invention and it is intended to cover the invention in accordance with the breadth and scope of the following claims.

I claim: I

l. A flash beacon for providing high power daytime flashes and relatively lower power nighttime flashes comprising:

a. A dual-mode capacitive discharge power supply having selectable large and small discharge capacities;

b. A gaseous discharge flashlamp connected to said power supply;

c. A dual-mode trigger circuit having selectable single repetitive trigger generator and group repetitive trigger generator connected to said flashlamp I for providing ionizing trigger pulses; and,

d. An automatic switch connected to said dual-mode capacitive discharge power supply and said dualmode trigger circuit for operating to select said small discharge capacity and said group repetitive trigger generator at night.

2. A flash beacon according to claim 1 wherein said automatic switch is a light sensitive switch.

3. A flash beacon according to claim 1 wherein said group repetitive trigger generator generates group pulses at a repetition rate within each group in the range of [5 to pulses per second.

4. A flash beacon according to claim 1 wherein said small discharge capacity is charged by said large discharge capacity through an inductance.

5. A capacitive discharge circuit for driving a flash lamp comprising:

a. A single high voltage DC power supply having first and second output terminals;

b. A first capacitor of a predetermined cpacity having first and second electrodes connected to said first and second output terminals respectively;

c. A second capacitor of substantially less capacity than said first capacitor having a first electrode connected to said first terminal and a second electrode;

d. A flash lamp having a first electrode connected to said first terminal and a second lamp electrode;

e. Switchable contacts for connecting said second lamp electrode to the second electrode of an alternative one of said first and second capacitors and actuated by a light sensitive relay connected for activating said contacts to connect the electrodes of said second capacitor across said flash lamp when the ambient light falls below a preset level;

a charging circuit for said second capacitor comprising an inductor connected between the second electrodes of said first capacitor and said second capacitor across said switchable contacts; and, g. A trigger circuit coupled to said flash lamp for triggering discharge of a connected one of said first and second capacitors through said flash lamp. =l l 

1. A flash beacon for providing high power daytime flashes and relatively lower power nighttime flashes comprising: a. A dual-mode capacitive discharge power supply having selectable large and small discharge capacities; b. A gaseous discharge flashlamp connected to said power supply; c. A dual-mode trigger circuit having selectable single repeititive trigger generator and group repetitive trigger generator connected to said flashlamp for providing ionizing trigger pulses; and, d. An automatic switch connected to said dual-mode capacitive discharge power supply and said dual-mode trigger circuit for operating to select said small discharge capacity and said group repetitive trigger generator at night.
 2. A flash beacon according to claim 1 wherein said automatic switch is a light sensitive switch.
 3. A flash beacon according to claim 1 wherein said group repetitive trigger generator generates group pulses at a repetition rate within each group in the range of 15 to 120 pulses per second.
 4. A flash beacon according to claim 1 wherein said small discharge capacity is charged by said large discharge capacity through an inductance.
 5. A capacitive discharge circuit for driving a flash lamp comprisIng: a. A single high voltage DC power supply having first and second output terminals; b. A first capacitor of a predetermined cpacity having first and second electrodes connected to said first and second output terminals respectively; c. A second capacitor of substantially less capacity than said first capacitor having a first electrode connected to said first terminal and a second electrode; d. A flash lamp having a first electrode connected to said first terminal and a second lamp electrode; e. Switchable contacts for connecting said second lamp electrode to the second electrode of an alternative one of said first and second capacitors and actuated by a light sensitive relay connected for activating said contacts to connect the electrodes of said second capacitor across said flash lamp when the ambient light falls below a preset level; f. a charging circuit for said second capacitor comprising an inductor connected between the second electrodes of said first capacitor and said second capacitor across said switchable contacts; and, g. A trigger circuit coupled to said flash lamp for triggering discharge of a connected one of said first and second capacitors through said flash lamp. 